Electrical photo-telescopic apparatus



July 31, 1928.

P. L. CLARK ELECTRICAL PHOTO TELESCOPIC APPARATUS Filed May 23, 1924 I5 Sheets-Sheet 1 FIGJ'I INVENTOR PM 1:. cQ k July 31, 1928.

P. L. CLARK ELECTRICAL PHOTO TELESGOPIC APPARATUS Filad May 23, 1924 3 Sheets-Sheet FIG. 27

\NVENTOR:

I47 132 I47 {481 49 I33 150 July 31, 1928. 1,678.974

P. L. CLARK ELECTRICAL PHOTO TELESCOPIC APPARATUS Filed May 23, 1924 3 Sheets-Sheet 5 NSULRTDD INVE NTO R "PM C- PATENT OFFICE.

PAUL L. CLARK, OF BROOKLYN, NEW YORK.

ELECTRICAL PHOTO-TELESGOPIG APPARATUS.

Application filed Bay 28, 1824. Serial No. 715,850.

The present invention relates to apparatus of a part of a receiving apparatus; Figs. 25

for the transmission and receiving of pietures, designs and the like, so that a visual image of the device at a transmitting station is reproduced by electric 4 wiring or radio broadcasting upon a projection screen, photographic plate or the like at a d stant receiving station. This reproduction is accomplished by transmitting pomt by po nt electrical values of the light values of 94.11acent points on the device to be transmitted, and synchronously reconvertinglthe electrical values transmitted into li t beams of proportional value, as describe in my pendin applications Ser. Nos. 627,815 and 655,- 02? issued as Patent 1,572,989, Feb. 16, 1926 and as understood in the art.

One object of the present invention is to provide adjustable means for bringing the apparatus into synchronism and step; another object is to provide means for securing a maximum amount of illumination on the picture; another object is toprovide a novel means for controlling the light intensity. Other objects of this invention are described in the following specification, shown In the drawings and further pointed out in the claims.

In the drawings, Fig. 1 is a plan view of a transmitter; Figs. 2, 3, 4, and 5. are sections of Fi 1 respectively on A-A, BB CC, and l)-D; Fig. 6 is a plan new of a mechanism for securing a uniform oscillatory motion; Figs. 7 8 and 9 are sect ons of Fig. 6 respectively at I EE, F-F and G-G; Fig. 10 is a detail view of an adJuStable mirror for use in the transmitting mechanism of Fig. 1; Fig. 11 is a d agram showing the paths of rays in a typical receiver; Fig. 12 is a front elevation and Fig. 13 is a section of Fig. 12 on H-H, showing a warping prism for use in the arrangement shown in Fig. 11; Fig. 14 is a front elevation and Fig. 15 is a section on Fig. 14 at KK, showing a special refractor for usein the arrangement of Fig. 11; Fig. 16 is a cross-section showing details of a magnetically actuated device for controlling the light beam in Fig. 11; Fig. 17 is a detail of a part of the device shown in Fig. 16; F g. 18 is a front elevation of a grid used in Fig. 11; Fi 19 is a front elevation of an aperture pl ate; Figs. 20, 21 and 22 are typical details of portions of aperture disks for use in the apparatus shown in Fig. 1; F1gs. 23 and 24 are a plan view and front elevation and 26 are an end elevation and a broken front elevation of a detail used in Fig. 23; Fig. 27 is a sectional view of an aperture disk or grid for use in either transmitter or receiver; Fig. 28 is a plan view showing the optical train for the receiver of Fi 23; Fig. 29 is a lan view showin a detail for varying the intensity of the light beam of Fig. 28; Fig. 30 is a detail of a part of one of the revo ving mirror groups of Fi 23, showing the maximum width of light cam required; Fig. 31 is a cross-section showing ad acent grids in a closed position; Fig. 32 1s a front elevation of an electro-magnetical- 1y controlled grid; Fig. 33 is a section on M-M, Fig. 32; Fig. 34 shows a slight modification of Fig. 32; Fig. 35 shows an alternative arrangement of the energizing coils of Fig. 32; Fig. 36 shows a diverging lens in the path of the rays between the pro'ector and the screen; Figs. 37, 38, 39, 40, 41 and 42 are elevations of several modifications of means for controlling the direction and intensity of the light beam of Fig. 28; Fig. 43 is a detail showing an adjustable base used in Figs. 37, 38, 39, or 42, if desired; Figs. 44 and 45 are a plan and cross-section showin a detail of a mirror support for use in 42 or elsewhere; Figs. 46 and 47 are detal s showing a mirror used in lace of the grid of Fig. 32; Fig. 48 is a etail showing a curved guide for use as in Fig. 42; Fig. 49 is a cross-section through the middle of Fig. 48 Fig. 50 is a front elevation showing a universal support for the device in Fig. 42; Fig. 51 is a plan view showing an optical train for an indicatin beam of light; Fig. 52 shows a slight modi cation of means for turning a light-controlling mirror; Fig. 53 is a front elevation showing electrical circuits for use in controlling the light; Fig. 54 is a front elevation showing an adjustably supported mirror; Fig. 55 is a front elevation showing a slight modification showing the mirror arranged oblique to a given axis; Fig. 56 is a front elevation showin a slight modification of Fig. 53; Figs. 5 58, 59 and 60 are typical diagrams of connections of compensating circuits required for light control; Figs. 61, 62 and 63 are slight modifications of light-control means; Fig. 64 is a detail of an insulating support for either end of the wires used in Figs. 42, 50, etc.; Fig. 65 is a front elevation showing a magnetically damped mirror clement; Fig. 66 is a plan view of an optical arrangement useful in pro ectmg the light re s from the receiver mirrors to a screen; ig. 67 is a diagram of circuitsfor the mirror system; Figs. 68 and 69 are slight modifications of the mirror supportmg system, as are also Figs. 70 and 71.

In Fi s. 1, 2, 3 4 and 5, a motor 1 dr ves a s indl e 2 which asses through bearings an is attached both to a gear 4 and worm 49. The gear 4 meshes with the gear 5 which is attached to a spindle 10 and also to an aperture disk 11. The worm 49 drives a gear 50 attached to a spindle 26 one portion 26 of which is rectangular and slides in a hollow shaft 28 provided with a. spiral slot 30. Fittin into the slot is the end of a screw 29 whic passes through the member 27, so that as the shaft 28 is slid to right or left the angular position of the shaft 27 of the gear 24 is changed with respect to the shaft 26-26. Longitudinal movement of the shaft 28 is effected by turning a thumb screw 43 fastened to the shaft 51 which carries a worm 42 which meshes with a toothed ortion of the member 39 which has a slidmg fit in a c linder 46. The member 39 is fastened to all bearings 40 which press against a circular flange 38 integral with the shaft 28, so that by turning the thumbscrew 43 the angular position of the gear 24 is changed with respect to the gear 50. The gear 24 meshes with an idler gear 22 which meshes with a gear 21 which drives a shutter 18 having suitable opaque and transparent portions. The gear 24 has cut in one face a spiral cam 31 (Fig. 5) with a proper return are. In this cam is a follower fastened to one end of an arm 33, the other end of this arm being attached to a shaft 34 fastened to a mirror 36 supported by a bearing 35, so that as the cam revolves, the mirror 36 is uniformly oscillated through an adjustable amplitude during three-quarters of the turn of the gear 24, the rest of the time being required for completing the cycle. Vanes 12 (Figs. 1 and 4) attached to the disk 11 will, when the disk is revolved, cause a current of air to raise the balanced shutter 13, pivoted at 14, to expose the aperture plate and the photo-electric cell (not shown) to the action of the li ht rays. A lens 52 converges rays reflected by a mirror 36 to focus upon the plane of the disk 11 an image of the picture to be transmitted (or to project the image when used as a receiver), the aperture plate 16 sharply defining the picture outline. The disk 11 and the structure supporting it (Fig. 3) may be oscillated if desired by suitable means, or it may be rigidly supported, depending upon the type of disk (Figs. 20, 21, 22) used. The motor 1 may be rigidly attached to a suitable base or be rotatably mounted, as shown in my pending applications, aforesaid.

In Fi 6, 7, 8 and 9 a gear 76 driven by suita le uniform speed or other means is fastened to a spindle 74 assing through bearings 75 and is also attac ed to the member 67 which revolves as the gear 76 is turned and carries a gear 73 meshing with an internal ear 77, so that as the member 67 is revolve about its axis 7466, the gear 73 turns around four times. The member 67 carries a star and cam (Geneva) movement 68, 69 71, the cam 69 being attached to the spindle 70, and the star 68 being attached to a spindle 66 passing through a bearing 65. Attached to the spindle 66 is a quadrant 63 (Fig. 9) engaging the toothed part 62 of an arm 60 pivoted at 61. This evice when used for oscillating purposes will roduce a substantially uniform reciprocating motion with a quick return.

In Flg. 10 the arm 33 is provided with a slotted detail 83 attached to a shaft 34 which is attached to the mirror 36, permitting angular adjustment of the mirror with respect to the arm 33.

In Fig. 11 rays 93 from a plurality of light sources or a multi-filament lamp 85 are received upon and reflected by a concave mirror 86 to focus upon transparent ortions of an opaque aperture plate or gri 87 and rays passing throu h t is grid are collected and conver ed by enses 88, 89 to fall upon an electrica y actuated diaphr m which reflects the ra s to pass throug a warping prism 91 an oblique lenses 92 to focus upon the plane of apertures in the disk 11, the function of this arrangement being to produce a curved ima e following the arc of a circle and of variale light intensity from a plurality of straight images of constant intensit In igs. 12 and 13 the warping prism 91 has a convex face 95 and a warped face 96, being similar to that described in my pending applications, aforesaid.

In Figs. 14 and 15 the width 0 of the curved lenticular surfaces is equal for each.

surface and the general angles of these lenses with respect to the axis of the member 92 is such as to secure the refractive function shown in Fig. 11, the curvature being such as to cause the refracted rays to fall upon the arc described by the apertures as the disk revolves.

In Figs. 16 and 17 an electro-magnet 100,

mounte in a suitable shell 109, actuates a stretched diaphragm 101 whose outer surface is plane, polished and reflecting. Adjustment for position and stretching of the diaphragm is accomplished by means of screws 108 and members 107, 109. Resting upon the plane surface of the diaphragm is a flat grating 105 supported by adjusting screws 106 carried by arms 104 attached to the shell 103, the stop 105 serving to limit the outward motion of the diaphragm when photo-electric impulses energize the coil 100.

In Fig. 18 the grid is of opaque material provided with opaque and transparent slots of equal width and has an adjustable support 116 for mounting in any desired position or for vertical and horizontal ad ustment.

In Fig. 19 the aperture plate has opa ue parts slightly separated to form a p urality of equi-spaced arcs. This plate is for use in place of a multi-filament source, and is to be illuminated by a large spot of light from an arc lamp.

In Fig. 20 the opaque disk 11 has a plurality of cqui-spaced, identical apertures 124 equidistant from the spindle 10, the distance between the apertures being equal to the width of the image of the picture to be reccived or transmitted.

In Fig. 21 the apertures 124 are arranged in a single SP1} al and in Fig. 22 in a plurality of successive spirals, the advantage of the latter arrangement being that a slower speed is necessary in covering a given field, and also that this modification may be used with a plurality of photo-electric cells, each successive spiral beginning where the previous spiral stops, to give a continuity of view.

In Figs. 23 and 24 a shaft 134 is driven by a constant speed or synchronized motor or by a combination of motor and hand control, and is attached to a shaft 128 by a coupling 133 (the same as 133, Fig. 26). The shaft 128 carries a gear 136 and a worm 129 which turns a gear 130 at a. ratio of, say, 200 to 1, bein supported by bearings 127. The gear 136 rives a. gear 137 fastened to a shaft 139 which passes through bearings 138 and drives a multiple mirror group 140 at high speed, say, 10,000 R. P. M. The ear 130 is connected to a shaft 129 supported by bearings 131 and lined up with a shaft 134 supported by bearings and connected to shaft 131 by a coupling 133, said shaft 134 also supporting a mirror group 141 at right angles to, above and overlapping mirror group so that a plane perpendicular to and passing through the middle of either group intersects the periphery of the meeting group 45 degrees off the vertical axis of said coacting group. In practice, these mirror groups should consist usually of not less than twenty mirrors, each group being of such width as to intercept light from two adjacent mirrors of the coacting group. All the mirrors in any group should be of identical size and reflection characteristics, juxtaposed and at the same angle with respect to and distance from their spindles.

In Figs. 25 and 26 a shaft 134 slides in the coupling tube 133 having a spiral slot in which slides a pin 151 ri idly fastened to the said shaft 134. A sha t 132 provided with a feather 147 sliding in a. keyway in the tube 133 permits the tube to slide with respect to both shafts which should be prevented from sliding by collars attached to the shafts and running against the bearings, so that any slidin of the tube 133 will cause an angular disp acement between the two shafts. The tube is slid by turning the knob 157 attached to the hollow screwthreaded iece 156 which is prevented from end play y a bearing 152. As the member 156 is turned the yoked iece 135, 154 is moved in the direction 0 the axis of the shafts 132, 134, the yoke being attached by suitable pins to a ring 148 which has a running fit between flanges 149 formed integral with the tube 133.

In Fig. 27 the aperture plate or grids 115 are protected by glass plates 160 held together by a clamped frame 158, 159. The aperture structure may consist of stri s of metal foil or wire, or may be electrop ated or photographed upon the glass plates. When hotographed upon the plates sharply defined thin surfaces may be secured with a high degree of accuracy and uniformity, since every grid can be an exact photographic copy of a standard grid.

In Fig. 28 a concave mirror 162 receives rays from a source 161 and directs them through a grid 163 to converge upon a shut ter 164 and pass to the lens 165 which converges them to fall upon a light-intensity controlling means 166 which reflects the rays to fall upon a grid 168 and pass through an aperture plate 169 to a lens 170 which con verges the rays to fell upon the mirrors 140, 141 (see Figs 23 and 24) which reflect the rays as shown at 142 to traverse the picture field or screens. The focal length of the lens 165 should be such that a substantial image of the grid 163 is formed at or near 168 and the focal length of the lens 170 should be such that the rays 142 converge to a substantial point at the screen plane or surfaces.

In Fig. 29 the member has two turned up ends 144 each of which is in the form of a grid, photo-electric impulses in the magnet coil 177 causing the grids to interce t a pencil of parallel rays 178 proportiona to the displacement of the member 175 which is pivoted at 176.

In Fig. 30 the beam of light rays should generally be of suflicient width to embrace two or more complete mirror faces of the group 141, and the beam should be rectangular in cross-section, the axis of the beam striking each mirror group 45 degrees off the vertical axis of said group.

In Fig. 31 grids 115, 115 are shown in relative closed positions. Either grid may be moved with respect to the other, or both moved simultaneously in opposite directions, in order to accomplish variations in the intplnsity of the light beam passing through t em.

Ill]

of the same polarity, and the coil 183 is of the same polarity as 181; so that variations in the magnetizing current in the coils 186 will cause varying oscillations of the grid 115.

In Fig. 34 the straight iron armature 188 and the curved bearing 189 are slight modifications of the arrangement shown in In Fig. 35 the armature 188 has three windings connected as shown, the leads 186 connectlng to a direct current supply, while the leads 186 connect to a source 0 photoelectric current. I

In Fig. 36 the ath of rays to the mirror 193 is shown by t e arrowed lines, the rays being reflected as shown to a diverging lens 191 which changes the angle of the beams passing through it, thereby determining the size of the icture on the screen.

In Fig. 3 a mirror 194 is pivoted at two points to electrical conductors 198, 199 attaehed to an insulating base 200. Wires 196 should be connected to apparatus for receiving and rectif ing one-half of the received broadcasted p oto-elect-ric signals, say, the positive half of the alternating sine wave as produced by a light chopper and photo electric cell of the transmitter circuits; and the leads 197 should be connected to apparatus for performing the rectifying of the negative half of each alternating cycle, as understood by those familiar with the broadcasting art.

In Fig. 38 a mirror 201 is held between the curved ends of conductors 202, 203, each conductor being connected as described for the arrangement shown in Fig. 37.

In Fig. 39 a mirror 207 is attached to the ends of adjacent conductors 208, 209, electrically connected at the top and bottom, but having different temperature expansion factors. lVires 210 should be connected to the signal receiving apparatus, the strength of which signals, properly amplified, will cause variable deflection of the mirror and cause a resultant change in the direction of the reflectedrays as shown in Figs. 11, 28, 51 and a change in the beam position with respect to a grid, as in Figs. 31, 32, etc.

In Fig. 40 a mirror 212 is attached to leads 213, 214 connected to terminals 215, 216 mounted on an insulator 219 fastened by a support 220 to a cooling liquid container 221. A common lead 145 and leads 217 connected to the terminals pass throu h a bushing 218 and should be connected to the signal receiver circuits, as in Fig. 37. Cooling gas or liquid dpassed through the orifice 222 will surroun the conductors 213, 214 and tend to stabilize and reduce their temperature; or the cooling means may be noncirculating in the chamber 226 and serve merely as a conductor of heat between the electrical conductors and an outer cooling chamber 227 provided with orifices 224 for the entrance and circulation of a cooling agent. Variation in the heating of the conductors produced by variations occurring in successive halves of each cycle of the radio frequency photo-electric current will cause the mirror 212 to oscillate and control the angle of reflection of a beam of light rojected to a suitable aperture plate, or chopper, thus permitting a eater or less amount of light to pass throng to the means employed for transmitting the light beam to traverse the screen in a succession of juxtaposed light bands, as understood in the art.

In Fig. 41 a column of mercury 232 is held in a glass tube 230. Leads 229 connected to, terminals 233 in the mercury column should be connected to the source of photo-electric current. Sudden heating and cooling of the column by the current variations will change the curvature of the meniscus 231 of the column and vary the dispersion of a beam of light projected upon and reflected by the surface of the meniscus, this surface being comparable to that of the diaphragm 90, Fig. 16.

In Fig. 42 a support 234 has end pieces 235, 236 provided with insulating bushings through which pass conductors 238, 239 which are separated at the middle by an insulating block 240 and connected by wires 238, 239, so that the circuit 238 is at the left below the insulator 240 and at the right above the said insulator, the circuit 239 also crossing over, as shown. The ends of the leads 238, 239 should be connected as described for Fig. 37, etc. The advantage of the above arrangement is that the mirror 241 is supported by four wires all in tension which will maintain the mirror in a neutral position, deflection being proportional to the intensity of heating currents in the conductors.

In Fig. 43 terminals 251, 252 (corresponding to any of the terminals shown in Figs. 37, 38, 40, 42) are connected to an insulator 250 carried by an arm 248 pivoted at 253 to an arm 245 pivoted at 244 to a member 243. A set screw 247 permits adjusting the angle between the arms 245, 248 which are separated by a spring 249. A tension spring 246 maintains constant tension in the conductors (as 238, 239, Figs. 42 and 50).

llll

The type of tension terminal here shown may be used at both or either top or bottom of any pair of conductors or supports; the inertia of its parts should, however, be greater than that of the photo-electrically controlled moving elements so that stresses of short duration in the said moving elements do not correspondingly affect the position of the supporting means.

In Figs. 44 and 45 the mirror 255 has lugs 256 over pivots in which pass looped wires 257, 258. If the mirror is of metal one or more of the wires should be insulated from the mirror, silk-covered wire being suitable. lVith the mirror thus insulated, an insulator, as 240, Fig. 42, will not be needed,

thus decreasing the weight of the movingv element.

In Fig. 46 a mirror 260, and in Fig. 47 a mirror 259, is attached to the armature 180 so that movement of the armature causes the mirrors to move through a predetermined angle and position so that light rays reflected by them will be suitably deflected to vary the quantity of light passing through an aperture plate, light filter or grids.

In Figs. 48 and 49 the member 270 has grooves 271 and a slot 273 serving as a hearing or steadying device for a conductor immersed in a circulating liquid, as in Figs. 40 and 42, each wire resting in a curved groove and so disposed that the mirror element is in the recessed portion 272, each member 270 being rigidly held in the proper position in the cooling chamber, and the wires being in tension, as described for Figs. 42, 43, 45, etc. This curved support is shown in my co-pending application, S. N. 13,306.

In Fig. 50 the light-reflecting element wires and support 241, 238, 239, 279 are flexibly or adjustably supported by arms on a member 277 turning in a bearing 280 on the arm 276 having a bearing which turns on a spindle 275 supported by a rigid bearing 274, the arrangement of the bearings being such that their axes are perpendicular to each other and intersect at the middle point of the mirror 241. This arrangement is convenient for changing the angle of the mirror with respect to the optical axis of the apparatus, in order to secure a maximum quantity of the light available for the picture and direct the light with the desired precision.

In Fig. 51 rays from the light source 282 pass through an aperture in the plate 283, fall upon a lens 285, are refracted to a mirror 286 and reflected by the mirror to a lens 287 which converges them to a point or line on the surface 288. WVhen the mirror is in the proper location with respect to the optical axis of the receiver the light falls upon a predetermined marked spot; but when the beam from the mirror is for any reason thrown off this spot, as shown at 290, adjustment for bringing the mirror back into its proper position is made by turning the device shown in Fig. 50, or by automatic or other compensating means, as described in connection with Figs. 53, 50, 57, 59, 43, etc.

In Fig. 52 movement is imparted to the pivoted mirror 293 by passing the conductors 213, 214 over a pu ley, so that uneven heating of the wires causes the mirror to change its position. The diagram of connections of the wires 213, 214 may be that shown in Figs. 37, 38, 42, 53, etc., it being considered within the scope of this invention that some or all of the features comprising any one or more than one of the several modifications illustrated or described are wholly or in part applicable to other modifications.

In Fig. 53 the wires 213, 214 are connected to the source or sources of incoming signals, as previously described, the circuits of these wires being insulated from the wires 313, 314 which are passed over a pulley or knob 296 which may be turned for adjustment but which is not free to turn by different degrees of tension in the wires. A source of potential 297 is applied across the terminals of the wires 313, 314 through an adjustable resistance 298, 299. Also across each terminal is shunted another circuit whose wires 300, 301 are disposed alternately and uniformly spaced, preferably with the spacing equal to the diameter of the wires, the function of these wires being to serve as a grid for automatically varying the current in the wires 313, 314 by shunting a variable amount of current when the wires are unevenly heated, so that if the wire 314, for example, becomes too long on account of the heating of wire 214 being too small, then the mirror 212 will reflect its beam of light too far to the right and cause the beam to fall on wires of the circuit 301, thereby heating these wires, increasing their electrical resistance and shunting more heating current through the wire 313 and less current through the wire 314, which tends to move the mirror back to a neutral position. The circuits 301, 302 may also be connected in series or series-multiple or in any feasible way across either the tension wires 313, 314, or across the mirror actuating wires 213, 214, or across both pairs of wires (as in Fig. 42) to provide the compensating feature, or for stabilizing the oscillating mirror system.

In Fig. 54 the mirror 308 is provided with a lug pivoted at 309 to links 310 which are pivoted to conductors 311 which correspond in function to the conductors shown in Figs. 37, 38,40, etc.

In Fig. 55 the wires or rods 213, 214 are attached to terminals 322, 323 which are attached to an oblique insulation block 320 which may be supported on an adjustable base, as in Fig. 43. The upper ends of the wires are flexibly attached to the oblique mirror 312 by means of rojections 315 paming through holes in the wires, each wire being preferably of the same length, material and cross-section between points of contact of the heating current leads, although the wires may be of difi'erent length, conductivity, cross-sectional area or shape, if desired; but both wires should usually have either a positive or a negative thermal expansion coeflicient. Attached to the mirror are also one or more wires 316 for use as tensional members to take up the slack in the system caused by the expansion of the lower wires when energized by the photo-electric impulses. The tension wires may be placed directly in line with the lower wires or at any convenient point or points on the mirror or mirror support. In order to keep the mirror normally in a plane parallel to its position at rest, I provide parallel wires 321 attached to the mirror, the ends of these wires being secured rigidly to a pair of supports (not shown) parallel to the mirror, i. e., the point of support of the mirror is equidistant for both the wires to the left rigid support, and also isequidistant for both the upper and lower right-hand wires. A weight or vane 318 for damping or deadbeating the wires is attached to one or more of the wires 316, or 213, 214, if desired. The mirror should ordinarily be rectangular, of approximately four times the projected area of the spot required for juxtaposition of adjacent lines on the screen; or of twice the projected linear dimensions (as viewed along the optical axis) of the actual mirror size required for the projection of a spot of light of necessary area on the screen with the light source and optical system of suitable design and size to cover entirel the mirror with a beam of substantially uniform light intensity throughout its cross-section. The sides of the mirror should be parallel to the axes of the revolving mirror groups (Figs. 24, 30, etc.) and the mirror 312 should be so supported that its path of oscillation is in a plane parallel to the optical axis of the ap aratus.

In Fig. 56 selenium stri s 325 are electrically connected to the wires 326, 327, in order to form light-sensitive means for varying the conductivity of the circuits. Each of the complete cells is designed to take the place of a stri on a grid, or osition-finder, for the light am; as descri d in connection with Figs. 51 and 53. The wires 326, 327 should be connected into a circuit to accomplish the shunting of electrical current as the wires 304, 305, 306, Fig. 53.

In Fig. 57, 328 and 329 are the tension wires of a system similar to that shown in Fig. 53. A source of potential or a battery 331 is connected through individual adjustable resistances 332, 333 across each branch,

correction of the mirror angle or position produced by mechanical or electrical effects or errors beyond the automatic scope of th apparatus to satisfactorily correct.

In Fig. 58 the wires 341, connected to a source of constant potential, are connected to the terminals of the wires 336, 337, an intermediate point 342 of which is connected to terminals of adjustable shunt resistances 338, 339, permitting the control of current in the tension wires 336, 337.

In Fig. 59 the grid consists of a series of photo-electric strips or cells 347, alternate cells being connected in series so as to form two circuits 343, 346 and 344, 345, one of each of these circuits bein in series or multiple with the tension wires of circuits such as shown in Figs. 53, 55, 57, etc., for control of the light beam position.

In Fig. 60 the apertures 351 in the grid are equally spaced and should exactly coincide with the apertures in the coacting grid, so that the light rays from the transparent arts of one grid should pass through or be intercepted by the coacting grid. On account of the aberration or non-rectilinear effect produced by ordinary lenses I prefer that the coacting grid be generally a photographic negative of the grid through which the light first passes, or vice versa, using as an ob ective the lens 165 or a duplicate thereof in the position it is to occupy in the optical train, for securing a pair of grids of the greatest efliciency. These grids need not he rectangular or in multiple, as a single aperture formed in an opaque piece of metal or on a photographic glass plate or film may be used in conjunction with its supplementary mate. At respectively the right and left of each aperture and located so as not to int-erfere with the passage of light through the aperture or apertures, are located a plurality 0 elements 350, 352 whose electrical conductivity varies with the light or heat of the rays falling upon them, these circuits being connected to t e tension wires of the mirror oscillating means, as described in connection with Figs. 53, 56, 57, etc., so that if the light beam falls either to the right or the left exceeding a predetermined value due to the erroneous functioning of the apparatus or the optical system, or to the excessive strength of signals the tension in the elastic wires attached to the mirror is changed by electrically varying their length by means of heating currents, producing in the tension means an oscillating system of a frequency depending upon the non-responsiveness, lag

or sluggishness of the photo-electrically controlled circuits and apparatus, due to inertia or momentum of the moving elements, and opposing the effect produced in the wlres (as 213, 214, Fig. 53) by the received signals the eli'ect of which a half cycle previous would be to throw the light rays on either the right or left series of cells; so that for every received photo-electric impulse affecting a change of length in the mirror wires (as 213, 214, Fig. 53) there is produced In the tension wires (as 313, 314. Fig. 53) a counter pull governed in effect by the strength of the photo-electric signals and following it during the latter half of the cycle; thereby shortening the period of return of the mirror to a normal position. Suitable amplifying apparatus and other accessories as used in audio reception of radio should be provided and used in conjunction with the apparatus and circuits herein shown.

In Fig. 61 a wire 353 is stretched between two insulating supports, signal current being supplied across the terminals and varying the length of the wire the same as in some types of hot-wire voltmeters. A spring 356 connected between a rigid su ort and a link 354 attached to a small whee caring on the wire keeps the wire stretched and varies the angle of the mirror support 357 moving parallel to one branch of the wire.

In Fig. 62 the mirror 361 is provided with one or more bearings 369 held between two parallel conductors 359, 362, so that any difference in variations of their length causes the mirror to oscillate. This arrangement may be sup orted horizontally, if desired, and one condiictor, only, used, the second conductor being replaced by a fiat hearing, so that as the conductor alternately increases and decreases in length by virtue of the photo-electric signal currents passing through it the mirror is oscillated through predetermined angles proportional to the strength and duration of the signals.

In Fig. 63 the tension wires 336, 337 are attached to the mirror supports 364, insulated from each other and also insulated from the signal wires 213, 214. The mirror oscillating system should generally be symmetrically balanced with respect to the optical axis.

In Fig. 64 the wire 239 is held in a chuck passing through insulation 370, bending and turning back into the piece 368 which passes throu h the insulation. Turning the nut 366 a justs the tension of the wire 239.

In Fig. 65 the mirror sup ort 240 held by wires 238, 239 (see Fig. 42 is damped by means of a permanent magnet 373 attached to it and normally centered and moving between poles of magnets 372, all three poles being the same.

In Fig. 66 the beam of light 377 produces a picture at or near the lane of the lens 375. The lens 376 is a pro3ection lens of the proper focal length to receive rays from the image formed at 375 and pro ect a picture of the required size at the screen surface.

In Fig. 67 the tension wires 379, 380 and the mirror actuating wires 383, 384 are connected between supports 385 one or both of which are rigid. These wires support a cross-piece 409 of conducting material which also supports the mirror if desired. In mul tiple with each wire is a circuit of variable resistance which is energized by a battery 379 permitting control at will of the current in each wire. The wires 383 and 384 are connected through a condenser 386 to the inn coming signal amplifying apparatus.

In Fig. 68 the wires 388, 399 correspond to the wires 314, 214, Fig. 53, or to any other pair of wires similarly used on opposite sides of the mirror or mirror support. The balanced cross-member 392 is cemented, welded or pivoted to the wire 388, 399 and also to the heavier wire or support 389, 393, both wires being fastened between one or more rigid insulating supports 394, so that as the wire 388, 399 varies the angle of the crosspicce 392 the center of gravity of the said cross-piece remains stationary.

In Fig. 69 the wire 396 corresponds to the wires 314-, 214, Fig. 53, or to any other pair of wires used on opposite sides of the mirror or mirror support. This wire is wrapped around a circular drum 395 having a hub 398 through which passes a flexible tension wire 397 cemented or welded to the hub, or having a sliding fit thereon.

In Fig. 70 the mirror support 492 is attached to wires 388, 390 and to a more elastic wire 493 which is adjustably carried by arms of the rigid member 404 to which the wires 388, 399 are attached or in which they have a sliding fit, so that as the member 492 is oscillated by movement of the wires 388, 399 its intertia causes the end attached to the wire 493 to move more slowly or more rapid- 1y than the end attached to the wires 388, 399, the relative speeds of the two ends being in the ratio of about two to one.

In Fig. 71 the mirror support 495 is attached to adjustably supported tension wires 496, 497 carried by the rigid yoked member 409, 419 to which the wires 388, 399 are attached, ofi' center if desired; the length, material, elasticity and tension of the wires 496, 497, and the distribution of mass of the member 495 being such as to cause different relative speeds of the two ends at the signal transmission frequency.

In the different modifications all electrical circuits, mirror amplitudes and other factors determining the successful design and operation of the several parts of the apparatus should be provided with suitable adjustments. An aperture plate of suitable size and design should be placed at or near the plane of the revolving aperture disk 11, Fig. 2, or the lens 375, Fig. 66. The screen used for displaying the picture should be spherical of a. radius equal to the len h of the light beam as measured along t e optical axis from the screen center to the oint of reflection of the beam from the mirror groups 140 or 141, Fig. 24; and in this connection it may be stated that the specular type oi screen shown in m Patents Nos. 1,122,192 and 1,279,262 will especially adapted.

I claim:

1. An apparatus for receiving hoto-electric im ulses and projecting the hght values of sai impulses to juxtaposed areas of a projection screen, comprising a light source, means for intercepting rays rom said source proportional to the strength of said impulses and directing means for directing the said rays after interception to traverse a plurality of juxtaposed bands of substantially equal length on a curved screen of radius equal to the distance between the screen and the said directing means.

2. An apparatus for receiving photo-electric impulses and projecting the light values of said impulses to juxtaposed areas of a projection screen, comprisin a light source, a screen, means controlled by the said impulses for varying the intensity of the light eam derived from the said source, a lens for receiving and converging the light beam, after it has been varied by the said means for varying the intensity, to a beam-positioning mirror governing the elevation and an independent beam-positioning mirror governing the departure of the intersection of said beam with said screen, independent control for varying each of said ositioning mirrors, the aforesaid lens directing the light beam to focus upon the said screen.

3. In a paratus for receiving photo-electric signa s and projecting the light values of said signals; a source of light on a given optical axis; light condensing means adjacent said source, receiving rays therefrom, and directing said rays in the form of a convergent beam; a grid comprising a plurality of alternately disposed areas substantially one-half of which alternate areas are adapted to transmit light rays to a second grid, said first grid being disposed in the path of said beam; an objective lens dis osed to receive rays transmitted by said gri and converge said rays toward a given point; means controlled by the aforesaid photoelectric signals disposed in the last mentioned point and adapted to deflect the light rays fa ling thereupon in the form of a. diverging beam; a second grid, substantiall similar to the first grid, disposed in the path of the last mentioned beam; and a lens adjacent said second grid; the said objective lens being disposed to focus an image of the grid substantially upon the said transmitting and light-intercepting areas, a

second grid comprising areas corresponding substantially in number and sequence with corresponding areas on the first grid but dissimilar in configuration to said corresponding areas on said first grid, and means for directing a distorted vibrating optical luminous image of the areas on the first of saidgrids for superimposition upon and variable registration with the areas comrising the second of said grids, said means including a light-deflector actuated by said electrical signals.

6. In apparatus for translating electrical signals into light signals, in combination, a pair of grids, means for projecting light through the first of said grids; means, including a light-deflector actuated by said electrical signals, for roducing a distorted luminous image of sai first id and vibrating said image relative to sai second grid.

7. In apparatus for translating electrical signals into light signals, in combination; a pair of fixed grids disposed a suitable distance apart; suitable optical means including a vibratory mirror controlled by said electrical signals, said optical means being disposed relative to said grids and focused upon each of said grids to produce a distorted optical image of one of said grids upon the surface of the other grid, one of said grids being a registered photograph of said distorted image.

8. In apparatus for translating electrical signals into light si nals, in combination; optical means including a vibratory mirror controlled by said electrical signals, a pair of fixed dissimilar grids each disposed a suitable distance from said mirror, one of said grids being a photograph of the other grid, said photograph belng produced by using said optical means for focusing.

9. In apparatus of the class described, the method of photographing a given subject, which consists in illuminating said subject, concentrating the rays from said subject upon a relatively small mirror, and directing the rays from said mirror upon a relatively large photoghaphic plate.

10. In apparatus for translating electrical signals into light signals, in combination; a fixed grid; optical means including a plurality of fixed lenses and a vibratory mirror controlled by said electrical signals, for forming on a given surface a vibrating gridlike luminous optical distorted image of said grid; and a second grid, comprising areas registering with corresponding areas of said distorted image, in said surface.

11. In apparatus for translating electrical signals into light signals, in combination; means for producing a plurality of closelyadjacent individual light beams derived from a common source; a screen; means for simultaneously and proportionally varying the amount of light in each of said beams responsive to said electrical signals; means for concentrating the rays com rising said beams to converge upon a smal area; and means for causing said area rapidly to traverse adjacent areas on said screen.

12. In apparatus of the class described, in combination, means for producing a gridlike luminous optical image of an intensity controlled by suitable electrical signals;

means for focusing the rays comprising said grid-like image upon a common focal area and means for rapidly reciprocating said area over a given focal surface.

13. In apparatus of the class described, in combination, means for producing electrical im ulses, a suitable view-receiving surface, a xed source of illumination, optical means for producing a plurality of images of said source, electrically-controlled means for simultaneously and pro ortionally varying the brilliancy of more t an two of said ima es, last said means being actuated by said e ectrical impulses, means for superimposing said plurality of images to form substantially a single image, and means for causing said single image to register upon and scan said view-recelvin surface.

In testimony whereof, I, AUL L. CLARK, have signed m name to this specification this 1% day 0 May, 1924.

PAUL L. CLARK.

CERTIFICATE OF CORRECTION.

Patent No. 1, 678,974.

Granted July 31. 1928. to

PAUL L. CLARK.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Page 3. line 104, for the word "screens" read "screen 8"; same page, line 109, for the word "surfaces" road "surface S"; page 8, line 110, claim 7, for the word "registered" read "registering"; and that the said Letters Patent should be read with these corrections therein that the some may conform to the record of the case in the Patent Office.

Signedsnd sealed this 26th day of March, A. D. 1929.

(Sell) M. J. Moore, Acting Commissioner of Patents.

rality of fixed lenses and a vibratory mirror controlled by said electrical signals, for forming on a given surface a vibrating gridlike luminous optical distorted image of said grid; and a second grid, comprising areas registering with corresponding areas of said distorted image, in said surface.

11. In apparatus for translating electrical signals into light signals, in combination; means for producing a plurality of closelyadjacent individual light beams derived from a common source; a screen; means for simultaneously and proportionally varying the amount of light in each of said beams responsive to said electrical signals; means for concentrating the rays com rising said beams to converge upon a smal area; and means for causing said area rapidly to traverse adjacent areas on said screen.

12. In apparatus of the class described, in combination, means for producing a gridlike luminous optical image of an intensity controlled by suitable electrical signals;

means for focusing the rays comprising said grid-like image upon a common focal area and means for rapidly reciprocating said area over a given focal surface.

13. In apparatus of the class described, in combination, means for producing electrical im ulses, a suitable view-receiving surface, a xed source of illumination, optical means for producing a plurality of images of said source, electrically-controlled means for simultaneously and pro ortionally varying the brilliancy of more t an two of said ima es, last said means being actuated by said e ectrical impulses, means for superimposing said plurality of images to form substantially a single image, and means for causing said single image to register upon and scan said view-recelvin surface.

In testimony whereof, I, AUL L. CLARK, have signed m name to this specification this 1% day 0 May, 1924.

PAUL L. CLARK.

CERTIFICATE OF CORRECTION.

Patent No. 1, 678,974.

Granted July 31. 1928. to

PAUL L. CLARK.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Page 3. line 104, for the word "screens" read "screen 8"; same page, line 109, for the word "surfaces" road "surface S"; page 8, line 110, claim 7, for the word "registered" read "registering"; and that the said Letters Patent should be read with these corrections therein that the some may conform to the record of the case in the Patent Office.

Signedsnd sealed this 26th day of March, A. D. 1929.

(Sell) M. J. Moore, Acting Commissioner of Patents. 

